Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1995-03-14
2001-03-20
Le, N. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S069000
Reexamination Certificate
active
06203144
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jetting device.
2. Description of Related Art
In recent years, non-impact type printing devices have superseded previously used impact type printing devices and have increasingly propagated in the market. Of these non-impact type printing devices, the ink jetting type printing device is more popular because it has the simplest printing principle and facilitates a color printing operation with high gradation. In this type of printing device, a drop-on-demand type printing device, in which only an ink droplet for printing is jetted, has rapidly increased in popularity in the market because of its high ink jetting efficiency and low running cost.
Examples of the drop-on-demand type printer include the Kyser type, as disclosed in Japanese Patent Publication No. 53-12138, and the thermal jet type, as disclosed in Japanese Patent Publication No. 61-59914. However, these types of printing devices have the following critical problems. With respect to the former, it is difficult to design the device with a compact size. With respect to the latter, ink is heated at a high temperature, thus requiring ink with a high heat-proof property.
To solve both of the above problems at the same time, a shear mode type, as disclosed in Japanese Laid-open Patent Publication No. 63-247051, is proposed as a new type of printing device.
FIGS. 3A and 3B
show a shear mode type of ink jetting device. As shown in
FIG. 3A
, the shear mode type of ink jetting device
10
comprises a bottom wall
20
, a ceiling wall
22
, a rigid wall
26
, an actuator wall
60
and an ink channel
24
, which is surrounded so as to be sealed and defined by the above walls.
The actuator wall
60
is formed of piezoelectric ceramic material that is polarized in a Z-direction perpendicular to the ceiling wall
22
and the bottom wall
20
, and it is firmly fixed to the bottom wall
20
and the ceiling wall
22
. The wall surfaces
65
and
66
of the actuator wall
60
are provided with metal electrodes
68
and
69
at the lower side thereof and with metal electrodes
68
′ and
69
′ at the upper side thereof so as to be spaced from the metal electrodes
68
and
69
. The metal electrodes
68
,
68
′,
69
and
69
′ are electrically connected to a controller C.
As shown in
FIG. 3B
, when ink is jetted, the controller C controls the metal electrodes
68
′ and
69
to be grounded and applies a driving voltage V to the metal electrodes
68
and
69
′. Through this operation, electric fields in opposite directions occur at the upper and lower portions of the actuator wall
60
. Therefore, the upper and lower portions of the actuator wall
60
are displaced by thickness shear in such directions that the volume of the ink channel
24
is reduced. This deformation of the actuator wall
60
pressurizes the ink in the ink channel
24
, so that an ink droplet is jetted from nozzles (not shown in this view) that intercommunicate with the ink channel
24
.
In the ink jetting device described above, the metal electrodes
68
′ and
69
are grounded, and the metal electrodes
68
and
69
′ are supplied with the driving voltage. Thus, the metal electrodes
68
,
68
′,
69
and
69
′ must be connected to the controller C. Accordingly, this ink jetting device has a disadvantage that a large number of connections between the controller C and the metal electrodes are required, and thus the manufacturing cost of the device is high.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an ink jetting device that has a small number of connections of metal electrodes to a controller and can be manufactured at low cost.
To attain the above and other objects, an ink jetting device according to the present invention includes a wall that constitutes at least a part of an ink channel and is formed of piezoelectric ceramic material polarized in one direction. A first electrode is formed wholly over one surface of the wall, a second electrode is formed partially on the other surface of the wall, and a third electrode is formed at a position not connected to the second electrode on the other surface of the wall. A controller is connected to the second and third electrodes but is not connected to the first electrode. The controller induces a potential difference between the second and third electrodes to deform the wall with a piezoelectric effect, whereby ink in the ink channel is pressurized and an ink droplet is jetted from the ink channel.
In the ink jetting device of this invention thus constructed, the controller induces the potential difference between the second and third electrodes so that an electric field in a direction perpendicular to the polarization direction of the wall is produced between the first and second electrodes. Simultaneously, an electric field in the opposite direction to the direction of the electric field occurring between the first and second electrodes is produced between the first and third electrodes. The wall is deformed by the piezoelectric effect of the piezoelectric ceramic material, and the ink is pressurized in the ink channel so that the ink droplet is jetted from the ink channel. As noted above, the controller is connected to the second and third electrodes, but it is not connected to the first electrode. Therefore, the electrical contact (connection) between the electrodes and the controller can be performed in a simple manner. Thus, the productivity is excellent, and the manufacturing cost can be reduced.
REFERENCES:
patent: 4095238 (1978-06-01), Kattner et al.
patent: 4879568 (1989-11-01), Bartky et al.
patent: 5548313 (1996-09-01), Lee
patent: 53-12138 (1978-04-01), None
patent: 61-59914 (1986-12-01), None
patent: 63-247051 (1988-10-01), None
Brother Kogyo Kabushiki Kaisha
Dickens C.
Le N.
Oliff & Berridg,e PLC
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